Thin film technology involves forming thin films on substrates widely used in semiconductors and chip resistors. Desirable substrates have the following characteristics: (1) low dielectric loss, (2) high electrical insulation, (3) high thermal conductivity, (4) low surface roughness, (5) strong adhesion for thin films, (6) low water absorption, (7) high glass transition temperature, (8) great mechanical strength, (9) high thermal shock resistance, (10) low material diffusion, and (11) low costs.
Highly sintered ceramic substrates (such as those containing more than 99% aluminum oxide, titanium oxide, zirconium oxide, aluminum nitride, titanium nitride, and zirconium nitride) are commonly used in thin film technology. Theses substrates have most of the characteristics listed above. However, the fabrication cost is high as polishing is required.